Sorry, 90210 stickler
Actually, it was Donna, not Kelly, who flashed her bra with Brenda and Steve's ex Celeste. Kelly had already left for Washington, D.C. to surprise Brandon by that time.
Here's some useless (maybe) trivia: Donna's bra was white, Brenda's blue, and Celeste's red and all appeared to be the same Victoria's Secret style.
I don't think John dated Celeste out of spite either, but it was obvious he enjoyed how much it bothered Steve. Celeste didn't understand Steve's problems with John until Donna and Brend filled her in. Celeste is the one that came up with the flash the bra to distract John trick after hearing about the real John.
I was so disappointed that the show took John Sears into the direction they did. I liked him with Kelly, other than the fact that she was two-timing Dylan at first. Not that I wanted her with Dylan though, I'm a Brenda/Dylan fan all the way. Back to John, I wouldn't have minded if they had made him a regular and kept him with Kelly for a while.